An X-ray computed tomography (“CT”) device is capable of obtaining a three-dimensional image including an internal structure of an object by carrying out reconstruction processing on the images of the object taken with X-rays from various directions. Hitherto, the features of the X-ray CT device have been used to observe minute internal defects, such as a void and a crack, in a metal part or a resin part or the like, to measure the complicated internal shape of an electronic part, and to analyze a cause of a failure. See Patent Documents 1 to 4, below.)
With the recent advance of digital technologies, an attempt to use an X-ray CT device as the core of a digital engineering system has begun. The digital engineering system represents the technology for integrating a sophisticated computer-assisted design (“CAD”)/computer-assisted modeling (“CAM”) system, a three-dimensional formative system, and a three-dimensional measurement system to achieve efficiency and high quality throughout the whole process from development to manufacture. Combining these technologies makes it possible to repeatedly design and make prototypes without making molds and to commercialize products in a short time and at low cost. A reduced risk in development is expected by sharing accurate and complete production and technological data.
As a three-dimensional measurement system, a digitizer, a light-section method and the like have been proposed. However, it is extremely difficult to measure the internal shape of an object to be measured by the foregoing methods although the methods permit accurate measurement of surface shapes. In contrast to the measurement methods, there has been proposed an ultrasonic diagnosis that is capable of determining the presence of an internal space. However, it is also difficult to accurately grasp an internal shape by the ultrasonic diagnosis. For these reasons, an X-ray CT device is expected as the only three-dimensional measurement system capable of also determining an internal structure.